1. Field of the Invention
This invention pertains to stents for use in intraluminal applications. More particularly, this invention pertains to a novel structure for such stents and a novel delivery tool and method.
2. Description of the Prior Art
Stents are widely used for numerous applications where the stent is placed in the lumen of a patient and expanded. Such stents may be used in coronary or other vasculature (such as carotid arteries or peripheral arteries), as well as other body lumens (e.g., biliary lumens).
Commonly, stents are cylindrical members. The stents expand from reduced diameters to enlarged diameters.
Stents may be self-expanding or may require the application of force to expand. Self-expanding stents are commonly formed of material which (when in the reduced diameter state) are biased to expand to the enlarged diameter. Such stents are carried on catheters with a sliding sheath placed over the stent and resisting the natural bias of the stent. At a desired delivery site, the sheath is retracted and the stent is free to expand to the enlarged diameter with an outer wall of the stent opposing and abutting an inner wall of the body lumen.
Non-self-expanding stents are commonly placed on a balloon catheter with the stent in the reduced-diameter state. So placed, the stent is advanced on the catheter to a placement site. At the site, the balloon is inflated to expand the stent to the enlarged diameter. The balloon is deflated and removed, leaving the enlarged diameter stent in place. So used, such stents are used to expand occluded sites within a patient""s vasculature or other lumen.
Examples of prior art stents are numerous. For example, U.S. Pat. No. 5,449,373 to Pinchasik et al. teaches a stent with at least two rigid segments joined by a flexible connector. U.S. Pat. No. 5,695,516 to Fischell teaches a stent with a cell having a butterfly shape when the stent is in a reduced-diameter state. Upon expansion of the stent, the cell assumes a hexagonal shape.
More recently, significant attention has been paid to stents having drug coatings. Such drug-eluding stents have been developed to address a restenosis problem associated with stents. Restenosis is the tendency of an occlusion to reappear after having been treated by a stent. An example stent having drug storing and metering capabilities is disclosed in U.S. Pat. No. 6,206,915, which is hereby incorporated by reference in its entirety. It is hoped that restenosis rates would reduce following the introduction of drug-coated stents were the drug-coating is selected to inhibit restenosis.
While having a potential to being a significant improvement in stent design, drug-coated stents continue to have defects in application. For example, there are few choices of drugs and dosages in drug-coated stents. Also, current designs of drug-coated stents deplete the drug coating over a relatively short period of time (e.g., a few days).
According to a preferred embodiment of the present invention, an intraluminal stent is disclosed comprising a reticulated tube having an un-deployed diameter and expandable to an enlarged diameter. When the tube is at the rest diameter, the tube has cell-defining portions with opposing surfaces defining an open cell bounded by the cell-defining portions.